Need your advice on a Diagnosis: Broken Valve Spring(s) on 944 Track Toy
03-01-2016, 11:06 PM
#1
Instructor
Thread Starter
Join Date: Aug 2015
Location: Washington, DC
Posts: 194
Likes: 0
Received 0 Likes
on
0 Posts
Need your advice on a Diagnosis: Broken Valve Spring(s) on 944 Track Toy
Well, folks, I went and got some expert ears to listen to my 944 which was exhibiting a severe stumble on acceleration.
I brought the car in to Intersport in McLean, Virginia. There, Charlie drove the car and, from just the test drive, he determined that I had at least one broken valve spring.
This also explained the rough idle which calms down a few seconds after the engine is revved. It's because the oil pressure built up from revving is preventing the valve(s) from closing, and after the oil pressure subsides at idle, the valve(s) can close and from then on it purrs.
Or, that's how I understood it from what Charlie explained. I was pretty amazed, to be honest, and I'm just really happy to have a solid diagnosis.
According to Charlie, I can replace the valve springs without removing the head. But when observing Van put his engine together in his excellent YouTube video, he assembled his springs with the head off the block, and his spring compression tool required access to clamp on to the valve disc itself.
How does one replace valve springs without removing the block?
Basically, I now have to research the repair, and determine if I want to attempt to do it myself. I have my first track event two Saturdays from now (on March 12-13). I'm nervous about tearing into the engine for the first time with that little time to spare.
The other consideration is the possibility that the valves are now damaged, or that there's play in the valve guides. I imagine if there were much play, this thing would be burning a lot of oil. It burns oil, because I have had to top off at recent track days, but not noticeably as far as smoking.
Anyway, I would like your thoughts on the issue. Should I try to do the job? What should I do while I'm in there? Timing belt?
If it turns out that I need a complete valve job, one estimate that was tossed around was about $2K. Does that sound in line?
Thanks everyone!
http://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1988-porsche-944-track-toy/105890/page1/
http://www.dogparkracing.com
I brought the car in to Intersport in McLean, Virginia. There, Charlie drove the car and, from just the test drive, he determined that I had at least one broken valve spring.
This also explained the rough idle which calms down a few seconds after the engine is revved. It's because the oil pressure built up from revving is preventing the valve(s) from closing, and after the oil pressure subsides at idle, the valve(s) can close and from then on it purrs.
Or, that's how I understood it from what Charlie explained. I was pretty amazed, to be honest, and I'm just really happy to have a solid diagnosis.
According to Charlie, I can replace the valve springs without removing the head. But when observing Van put his engine together in his excellent YouTube video, he assembled his springs with the head off the block, and his spring compression tool required access to clamp on to the valve disc itself.
How does one replace valve springs without removing the block?
Basically, I now have to research the repair, and determine if I want to attempt to do it myself. I have my first track event two Saturdays from now (on March 12-13). I'm nervous about tearing into the engine for the first time with that little time to spare.
The other consideration is the possibility that the valves are now damaged, or that there's play in the valve guides. I imagine if there were much play, this thing would be burning a lot of oil. It burns oil, because I have had to top off at recent track days, but not noticeably as far as smoking.
Anyway, I would like your thoughts on the issue. Should I try to do the job? What should I do while I'm in there? Timing belt?
If it turns out that I need a complete valve job, one estimate that was tossed around was about $2K. Does that sound in line?
Thanks everyone!
http://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1988-porsche-944-track-toy/105890/page1/
http://www.dogparkracing.com
03-01-2016, 11:17 PM
#2
Rennlist Member
To remove the valve springs, you need to keep the valve in place (not moving up and down) while you compress the spring (so the keepers can be removed). Technically it's possible with the head on, but you would need a way to brace the valves using only what's in the combustion chamber or can be inserted in there, and compress the spring using only mounting points on the topside of the head. Maybe you could push against a TDC piston, or a coiled up rope inserted through the spark plug hole? It would be a lot nicer to do it with the head off though. And a head rebuild for $2k is crack pipe money.
03-01-2016, 11:22 PM
#3
Rainman
Rennlist Member
Rennlist Member
My experience with a broken valve spring on a 944 is that it makes an AWFUL racket...really ungodly type of rattling sound.
If you want to try on the car, you can use compressed air through the spark plug hole to hold the valve in place.
But the head is pretty easy to take off - 2-3 hours for an NA if you know your way around the 944 engine.
I wouldn't pay more than $500 including parts for a fully rebuilt head (head cleaned, new valve guides and seals, and gasket surface cut to be smooth and flat again). Out here I have gotten some 944 heads done at a big shop for $250 including parts. I'm sure there's something comparable in DC area.
For $2000 for a head job, "they" had better include a new set of timing and balance belts, rollers and pulleys, and water pump, all installed.
If you want to try on the car, you can use compressed air through the spark plug hole to hold the valve in place.
But the head is pretty easy to take off - 2-3 hours for an NA if you know your way around the 944 engine.
I wouldn't pay more than $500 including parts for a fully rebuilt head (head cleaned, new valve guides and seals, and gasket surface cut to be smooth and flat again). Out here I have gotten some 944 heads done at a big shop for $250 including parts. I'm sure there's something comparable in DC area.
For $2000 for a head job, "they" had better include a new set of timing and balance belts, rollers and pulleys, and water pump, all installed.
03-02-2016, 03:29 AM
#4
Rennlist Member
$2,000.00 is in line with what I'd pay for a shop to do that work in my area. That's the pulling and replacing the head on the vehicle. I paid well over $1k just to get my head rebuilt. It was $560.00 in labor, and I forget how much in parts. I do recall paying $300.00 or so just for the springs. Add in new valves, keepers, retainers, spring seats, and there's a reason why I don't want to remember the total price. 944 2V heads don't look much more than small block Ford or Chevy heads, but they sure are different in the cost of refurbishing them!
My experience with a broken valve spring on a 944 is that it makes an AWFUL racket...really ungodly type of rattling sound.
If you want to try on the car, you can use compressed air through the spark plug hole to hold the valve in place.
But the head is pretty easy to take off - 2-3 hours for an NA if you know your way around the 944 engine.
I wouldn't pay more than $500 including parts for a fully rebuilt head (head cleaned, new valve guides and seals, and gasket surface cut to be smooth and flat again). Out here I have gotten some 944 heads done at a big shop for $250 including parts. I'm sure there's something comparable in DC area.
For $2000 for a head job, "they" had better include a new set of timing and balance belts, rollers and pulleys, and water pump, all installed.
If you want to try on the car, you can use compressed air through the spark plug hole to hold the valve in place.
But the head is pretty easy to take off - 2-3 hours for an NA if you know your way around the 944 engine.
I wouldn't pay more than $500 including parts for a fully rebuilt head (head cleaned, new valve guides and seals, and gasket surface cut to be smooth and flat again). Out here I have gotten some 944 heads done at a big shop for $250 including parts. I'm sure there's something comparable in DC area.
For $2000 for a head job, "they" had better include a new set of timing and balance belts, rollers and pulleys, and water pump, all installed.
03-02-2016, 08:28 AM
#5
Addict
Rennlist Member
Rennlist Member
You can use a piece of clothesline fed into the spark plug hole to keep the valve from dropping while you replace a valve spring. Care must be taken of course. There are probably some youtubes on it. You can also use a fitting to blow air into the cylinder to hole the valve shut, this is not a bad idea to try as it will tell you if the valve will seat if the spring is replaced. In this case you want to do something to keep the engine from turning over unexpectedly, either direction.
Since the timing belt and cambox has to come off I'd wonder what other work might also be needed, you are not far off from having the head off and what else, do you need rod bearings? You probably need a set of valve springs, they are probably all pretty tired and there might be a better choice for what you are doing.
I'd consider hucking a good used running motor into it and going driving while you inspect this motor at your leisure. An engine is just a component in a race car like a steering wheel, set of brake pads or persistent cloud of profanity. Fixing one thing on this motor is probably going to mean doing that job over again soon, fixing something related.
-Joel.
Since the timing belt and cambox has to come off I'd wonder what other work might also be needed, you are not far off from having the head off and what else, do you need rod bearings? You probably need a set of valve springs, they are probably all pretty tired and there might be a better choice for what you are doing.
I'd consider hucking a good used running motor into it and going driving while you inspect this motor at your leisure. An engine is just a component in a race car like a steering wheel, set of brake pads or persistent cloud of profanity. Fixing one thing on this motor is probably going to mean doing that job over again soon, fixing something related.
-Joel.
03-02-2016, 10:20 AM
#6
Rainman
Rennlist Member
Rennlist Member
$2,000.00 is in line with what I'd pay for a shop to do that work in my area. That's the pulling and replacing the head on the vehicle. I paid well over $1k just to get my head rebuilt. It was $560.00 in labor, and I forget how much in parts. I do recall paying $300.00 or so just for the springs. Add in new valves, keepers, retainers, spring seats, and there's a reason why I don't want to remember the total price. 944 2V heads don't look much more than small block Ford or Chevy heads, but they sure are different in the cost of refurbishing them!
I only charge people $1500 for head gasket/belts/water pump jobs, including all parts and head rebuild...
03-02-2016, 12:23 PM
#7
Instructor
Thread Starter
Join Date: Aug 2015
Location: Washington, DC
Posts: 194
Likes: 0
Received 0 Likes
on
0 Posts
Thanks everyone.
I guess the reality is that I don't have the tools or experience to be ripping the cam off this engine. At least, not without taking my time about it. Doing this myself would come with some conditions: If I had a garage and not just a driveway. Either that, or if I had a month of Saturdays and not just ten short days to get it done.
I like the idea of a second engine, but I don't have the room for an engine lying around. The swap is actually more within my comfort zone, but it's still a job that would take far too long for a first-timer like me, even if I could quickly source one.
So I'm taking the car back in tomorrow to have them tear into it. I'm hoping it will be reasonable $ to do just the springs. Normal ones. Nothing fancy. Just do the minimum and make it run right.
I guess the reality is that I don't have the tools or experience to be ripping the cam off this engine. At least, not without taking my time about it. Doing this myself would come with some conditions: If I had a garage and not just a driveway. Either that, or if I had a month of Saturdays and not just ten short days to get it done.
I like the idea of a second engine, but I don't have the room for an engine lying around. The swap is actually more within my comfort zone, but it's still a job that would take far too long for a first-timer like me, even if I could quickly source one.
So I'm taking the car back in tomorrow to have them tear into it. I'm hoping it will be reasonable $ to do just the springs. Normal ones. Nothing fancy. Just do the minimum and make it run right.
Trending Topics
03-02-2016, 12:27 PM
#8
Instructor
Thread Starter
Join Date: Aug 2015
Location: Washington, DC
Posts: 194
Likes: 0
Received 0 Likes
on
0 Posts
Also, I should note, the $2 - $2.5K notion was a racing setup with all the tricks. Ported, tricked out springs, and so on. I'm not signed up for that.
03-02-2016, 12:38 PM
#9
Addict
Rennlist Member
Rennlist Member
IMO you are nuts if you do not get a full set of valve springs at the very least. With the cambox off I can probably do valvesprings in 30 mins a jug, or less. With seals, naturally.
03-02-2016, 01:08 PM
#10
Just a car guy
Rennlist Member
Rennlist Member
Join Date: Jan 2002
Location: South Lyon, Michigan, Ewe Ess Eh
Posts: 9,927
Received 835 Likes
on
524 Posts
Either learn how to do it yourself or pay someone to do it.
The only reason I can afford to have these cars is because I do the work myself. In fact, my S2 was bought not knowing for sure why it had a dead cylinder. As I suspected, it was a broken valve spring.
My wife's car, Penelope, also had a broken spring which we broke at 944Fest about 6 or 7 years ago while on the track at Nelson Ledges.
Here is the link to the S2 work: https://rennlist.com/forums/924-931-...ell-as-is.html It's a bit more complicated than a 2.5 job, but with a few tools and a lot of patience, it can easily be done.
Why anyone would try to do this without removing the head is beyond me. Wouldn't the piece of mind knowing a new head gasket is in place, and everything else gets looked at, be worth the extra cost and effort?
Consider this - take the same amount of money you would pay to have this done and buy some tools and a copy of the service manual. Learn how to do it yourself and then do it yourself. You will be a lot wiser for it. You've got a ton of help here if you need it.
The only reason I can afford to have these cars is because I do the work myself. In fact, my S2 was bought not knowing for sure why it had a dead cylinder. As I suspected, it was a broken valve spring.
My wife's car, Penelope, also had a broken spring which we broke at 944Fest about 6 or 7 years ago while on the track at Nelson Ledges.
Here is the link to the S2 work: https://rennlist.com/forums/924-931-...ell-as-is.html It's a bit more complicated than a 2.5 job, but with a few tools and a lot of patience, it can easily be done.
Why anyone would try to do this without removing the head is beyond me. Wouldn't the piece of mind knowing a new head gasket is in place, and everything else gets looked at, be worth the extra cost and effort?
Consider this - take the same amount of money you would pay to have this done and buy some tools and a copy of the service manual. Learn how to do it yourself and then do it yourself. You will be a lot wiser for it. You've got a ton of help here if you need it.
03-02-2016, 01:40 PM
#11
Rennlist Member
+1 to what Scott said... you could DIY and put the money you save toward a new set of springs. Plus when you order the HG kit for $100 (IIRC) it comes with seals for the cam tower too...so you can reseal it at the same time (easy job).
Pulling and installing the head is really not hard, I pulled one in about an hour using hand tools (engine out) and a buddy and I have pulled one on his car in less than 45 minutes in an apartment parking lot (engine in). We're just casual wrenches, not mechanics. Biggest hassle is removing all the stuff from the head like fuel rail, manifold, header nuts, etc and making sure nothing is stripped.
2 tools I strongly recommend... 1) get yourself some Irwin extractors for internal drive fasteners. $20 for a set of 5 at Lowes, fits all the allen head bolts on the car and many of the studs. 2) get a quality 6mm long allen socket for the internal cam tower bolts (beneath the 6 plugs). You can't fit an off-the-shelf extractor in there and you want to do it right. I paid like $8 shipped for a used Matco one.
Pulling and installing the head is really not hard, I pulled one in about an hour using hand tools (engine out) and a buddy and I have pulled one on his car in less than 45 minutes in an apartment parking lot (engine in). We're just casual wrenches, not mechanics. Biggest hassle is removing all the stuff from the head like fuel rail, manifold, header nuts, etc and making sure nothing is stripped.
2 tools I strongly recommend... 1) get yourself some Irwin extractors for internal drive fasteners. $20 for a set of 5 at Lowes, fits all the allen head bolts on the car and many of the studs. 2) get a quality 6mm long allen socket for the internal cam tower bolts (beneath the 6 plugs). You can't fit an off-the-shelf extractor in there and you want to do it right. I paid like $8 shipped for a used Matco one.
03-02-2016, 01:45 PM
#12
Instructor
Thread Starter
Join Date: Aug 2015
Location: Washington, DC
Posts: 194
Likes: 0
Received 0 Likes
on
0 Posts
IMO you are nuts if you do not get a full set of valve springs at the very least.
Scott said:
Either learn how to do it yourself or pay someone to do it.
You guys have me flipflopping on this decision like crazy. I want to do it myself. I really do. But do I have time to order the special tool(s) I'll need, head gasket, cam cover gasket, timing belt (possibly) and all the other while-yer-in-there stuff?
And then when I get it apart to the point where I realize I need another tool not sold in stores, do I have time to wait another couple days before finishing the job?
I'm very torn on this one. I'll also throw out there that I still have my Ford Fiesta ST that could do the job at the SCCA PDX event I'm signed up for next weekend, March 12-13. Or there's still time to back out of the event and give my spot to someone on the waiting list.
So doing it myself is still an attractive option, particularly with your help!
03-02-2016, 01:56 PM
#13
Just a car guy
Rennlist Member
Rennlist Member
Join Date: Jan 2002
Location: South Lyon, Michigan, Ewe Ess Eh
Posts: 9,927
Received 835 Likes
on
524 Posts
Scott said:
I love your thread. Especially the first page where you say you're not interested in working on it and "carlege" says "..and you bought this car because....." Funny.
You guys have me flipflopping on this decision like crazy. I want to do it myself. I really do. But do I have time to order the special tool(s) I'll need, head gasket, cam cover gasket, timing belt (possibly) and all the other while-yer-in-there stuff?
And then when I get it apart to the point where I realize I need another tool not sold in stores, do I have time to wait another couple days before finishing the job?
I'm very torn on this one. I'll also throw out there that I still have my Ford Fiesta ST that could do the job at the SCCA PDX event I'm signed up for next weekend, March 12-13. Or there's still time to back out of the event and give my spot to someone on the waiting list.
So doing it myself is still an attractive option, particularly with your help!
Are you on a specific schedule? You're not going to have this car ready in 10 days no matter what. Take your time, follow a step-by-step plan and take notes. Anticipate what parts and tools are needed and try to have them ready when you need them. A couple of days of waiting for something to arrive is a minor detail. You should be able to find something else to look at of fix while waiting.
And another thing - you'd be crazy not to have another car to drive other than the 944. Whether it be a Fiesta or something else. Any car pushing 30 years of age is going to be out of action once in a while.
03-02-2016, 02:15 PM
#15
Rennlist Member
If you ordered all your parts at once I don't see why you couldn't do it in 10 days. just be extra careful with stripping and shearing fasteners! Start soaking them in PB blaster. You don't need any exotic tools besides standard timing belt tools and a proper torque wrench. If you bring your head to a machine shop for R&R, they can replace the valve springs for you and save you the hassle of buying and using a valve spring compressor. The only way you could mess it up would be to mess up reinstalling the head/cam tower/etc.